The invention disclosed herein relates to dynamoelectric machines and more particularly, to an improved means and method for readily applying a winding-clamping annulus in rigid, supporting position against axial or radial displacement of the windings.
In the manufacture of large dynamoelectric machines it is common practice to utilize form-wound coils for assembling an energizing winding in pre-formed slots of the laminated stator cores of the machines. The ends of such coils typically extend beyond the stack of stator laminations and are subjected to electrodynamic and mechanical forces that cause the coils to vibrate relative to the stator and to one another. Such forces frequently reach relatively large magnitudes due to the high current passed through such machine windings during starting and peak load operating conditions. These electrodynamic forces are additive with the mechanical vibrations developed in the machine windings by their normal rotation during operation. The designers of dynamoelectric machines have long recognized that such vibrations of the end turns is undesirable because it destroys the winding insulation and can lead to premature electrical failures within the windings.
In response to this recognized need, various prior art bracing arrangements have been developed in an attempt to more adequately support the winding end turns against relative movement during their normal anticipated application. An early example of such a supporting arrangement is shown in U.S. Pat. No. 967,240 which issued on Aug. 16, 1910 and shows a dynamoelectric machine having a pair of rings for clamping a coil around the end turns of a set of windings to force them into engagement with an inner supporting ring. In the intervening years since the issuance of that early patent, other more suitable means have been developed for better supporting such clamping rings in rigid position with respect to winding end turns. For a number of years, for example, clamping rings were lashed to winding end turns with cords or roving material that was bonded to the windings by being dipped in an insulating resin after the cords were tied in a suitable operating position, thereby to rigidify the entire winding end turn structure. Although such tying arrangements were effective for providing the desired rigid end turn configuration sought, they were relatively expensive to install and difficult to repair, thus they gave way to various types of tieless bracing arrangements.
In such so-called tieless winding arrangements, adjustable brackets and clamping bolts are frequently used to secure the winding end turns of a machine in a desired rigid operating position. One example of such a tieless supporting arrangement is shown in U.S. Pat. No. 3,293,472 which issued on Dec. 20, 1966 and is assigned to the assignee of the present invention. Likewise, an improved version of a similar tieless winding support is shown in U.S. Pat. No. 3,320,452 which issued on May 16, 1967 and is assigned to the same assignee. A particular advantage of these relatively recent tieless bracing arrangements is that they include adjustable means for selectively moving a coil positioning ring in both a radial and axial direction with respect to the stator of a machine. This adjustability feature makes it possible to reposition the winding supporting ring in the field after the machine has left the factory. A disadvantage of the type of winding supporting arrangement shown in those patents is that they require the provision of considerable access room outside of the winding end turns in order to enable workmen to reach the ring adjustment means. The provision of such additional structured space for manufacturing purposes tends to be undesirably expensive in many large dynamoelectric machines.
Even more recently, as shown in U.S. Pat. No. 3,924,149 which issued on Dec. 2, 1975 and is assigned to the same assignee as the present invention, a dynamoelectric machine winding end turn supporting arrangement has been developed that enables a clamping annulus to be compressed against the windings of the machine in their assembled position, without requiring the provision of large amounts of operating room to make such a manufacturing installation and adjustment.
Accordingly, it is a primary object of the present invention to provide a tieless stator end turn supporting arrangement and method that overcomes the disadvantages and objections of related prior art supporting arrangements and methods.
Another object of the invention is to provide a tieless dynamoelectric machine end turn supporting arrangement that incorporates a movable adjustment means for simultaneous movement in both radially inward and axial directions relative to the end turns to apply a compressive force to a winding-supporting annulus and winding end turns therein.
Yet another object of the invention is to provide a tieless supporting arrangement for dynamoelectric machine winding end turns that is readily manufactured and assembled and that provides a more reliable winding support than is known to be afforded by related prior art supporting structures.
A further object of the invention is to provide an improved method for bracing the winding end turns of a dynamoelectric machine in a relatively rigid operating position.
Additional objects and advantages of the invention will become apparent to those skilled in the art from the description of it that follows taken in conjunction with the accompanying drawings.